The present invention relates to a radial scan, forward viewing ultrasonic endoscope having, at the tip of an insertion portion, objective optics for optical examination of the area ahead of said insertion portion and an ultrasonic probe for performing radial scan by ultrasound.
For ultrasonic endoscopes that can optically examine a body cavity while performing ultrasonic scan, it is generally considered advisable to project ultrasonic waves from the tip of an insertion portion to perform lateral scan on the area which lies the nearest to the scanning direction to be examined optically. The conventional ultrasonic endoscopes are structurally designed to meet this requirement.
However, the greatest value of ultrasonic endoscopes lies in inserting the ultrasonic endoscope into an accessible organ adjacent to the inaccessible organ which has problems and performing ultrasonic scan from the accessible organ by obtaining an ultrasonic cross-sectional image of the other side of an abnormal area of the mucous membrane in the body cavity of interst.
Therefore, effective ultrasonic scan is inmost cases radial scan about the longitudinal axis of the tip of the insertion portion whereas effective optical examination is forward viewing which is most convenient for checking the area ahead of the insertion portion of the endoscope as it passes through the body cavity.
However, ultrasonic endoscopes of this type that are commonly called xe2x80x9cradial scan, forward viewing ultrasonic endoscopesxe2x80x9d have several problems to solve, such as designing a structure that can shorten the rigid tip, and no commercial product has been put on the market.
An object, therefore, of the present invention is to provide a practically feasible radial scan, forward viewing ultrasonic endoscope that can minimize the length of the rigid tip of the insertion portion.
This object of the invention can be attained by a radial scan, forward viewing ultrasonic endoscope having an ultrasonic probe that is formed in annular shape to perform radial scan and which is provided at the tip of an insertion portion and a tip body that is fitted with objective optics for examining the area ahead of the insertion portion and that has a smaller outside diameter in the front half which is fitted into the ultrasonic probe, characterized in that centering mating portions that permit the outer surface of the ultrasonic probe and that of the tip body to meet flush with each other at the boundary are formed in the ultrasonic probe and in the tip body, and that the gap between the inner peripheral surface of the ultrasonic probe and the mating surface of the front half of the tip body is formed to be larger than the gap bet ween the centering mating portions.
In a preferred embodiment, the ultrasonic probe has an array of ultrasonic vibrators and an annular receptacle for holding the array of ultrasonic vibrators, the front half of the tip body is fitted into the internal space of the array of ultrasonic vibrators, and the centering mating portions are formed in the receptacle.
The present disclosure relates to the subject matter contained in Japanese patent application No. 2000-136733 (filed on May 10, 2000), which is expressly incorporated herein by reference in its entirety.